Low friction tubular conveyors



6, 1966 J. M. LEACH 3,266,619

LOW FRICTION TUBULAR CONVEYORS Filed July 31. 1964 2 Sheets-sneer. 1

INVENTOR.

QVLLZML J. M. LEACH 3,266,619

LOW FRICTION TUBULAR CONVEYORS Aug. 16, 1966 2 Sheets-Sheet 2 Filed July 51, 1964 INVENTOR The present invention relates to conveyors, and, more particularly, to conveyors of the tubular type.

Tubular conveyors usually consist of an exterior housing or casing in the form of a tube, and a series of pushers or flights suitably linked together and propelled along the interior of the casing by a suitable drive unit. Bulk material to be conveyed is introduced into the tube at a desirable charging point and carried along the interior of the tube and ejected from the casing at a desirable discharging point or points.

Sliding friction exists between the pushers and tube as well as between the material being conveyed and the pushers and tube. This sliding friction becomes impractically high when abrasive materials are conveyed, particularly when the conveyor is long and includes a number of turns, because the high friction raises the force or pull required to propel the pushers along the tube to a prohibitive figure, causes excessive wear on all of the components of the conveyor and frequently causes an undesirable powdering of the material.

It is an object of the present invention to provide a tubular conveyor in which sliding friction is substantially eliminated.

It is another object of the present invention to provide a tubular conveyor in which the turns introduce rolling instead of sliding friction and at the same time are not prone towards stoppages due to jamming of the material being conveyed between the turns and pushers.

It is still another object of the present invention to provide a tubular conveyor in which the horizontal tubing runs, the vertical tubing runs and the turns are provided with friction reducing instrumentalities.

It is yet another object of the present invention to provide a tubular conveyor having turns which impose only rolling friction to the movement of the pushers and are substantially free from areas where residual material will accumulate.

It is a further object of the present invention to provide a tubular conveyor having the horizontal and inclined runs shaped so as to minimize sliding friction between them and the pushers.

It is a still further object of the present invention to provide a tubular conveyor in which the tubular runs are provided with expansion areas which eliminate packing of thematerial being conveyed into tight areas, which expansion areas do not cause accumulation of residual material.

Other objects and advantages of the present invention will become apparent to those skilled in the are upon recourse to the following specification and the attached drawings which illustrate what are now considered the preferred embodiments of the present invention.

In the drawings:

FIG. 1 is a side view of a typical layout of the tubular conveyor of the present invention;

FIG. 2 is a side view of a turn component of the present invention;

FIG. 3 is a sectional view taken substantially on the plane indicated by line 33 of FIG. 2;

FIG. 4 is a sectional view taken substantially on the plane indicated bylines 4-4 of FIGS. 2 and 5.

FIG. 5 is a sectional view taken substantially on the plane indicated by line 5-5 of FIG. 4, and

FIG. 6 is a partly sectioned view of an expansion area of the present invention as applied to a sliding friction turn.

3,266,619 Patented August 16, 1966 For the purpose of explanation a typical but uncomplicated layout of the tubular conveyor of the present invention is shown in FIG. 1 wherein the entire conveyor lies in the same plane, but it is to be understood that.

the path of the tubular components can with equal facility extend into planes at angles to that shown.

The friction-reducing components of the tubular conveyor of the present invention can be utilized with pusher and linkage constructions of any type, but for maximum results it is preferable to use the pusher-linkage assemblies disclosed in co-pending application No. 222,330, filed September 10, 1962, now Patent No. 3,216,553. Such a pusher-linkage assembly is shown at 10 in FIG. 3 but have been omitted from the other views for the sake of clarity of illustration of the novel components of the present invention.

A drive unit such as that disclosed in the aforementioned application is shown at 12 in FIG. 1 and propels the pusher-linkage assemblies in the direction shown by the arrow.

A substantially straight section of tubular casing 14 directs the pusher-linkage assemblies to a wheel turn 18 which will be described in detail later in this specification. Throughout the conveyor the various components are usually connected together by suitable couplings 16 which within themselves are not a part of the present invention. Another section of horizontal tubing directs the pusherlinkage assemblies to a second wheel turn 18. The tubing section 20 is curved for a reason which will be described in detail later in this specification. A vertical section of tubing 22 connects the last described wheel turn 18 with another wheel turn 18 located above the last described wheel turn in the layout example shown. The vertical tubing 22 is provided with an expansion section 24 and the lower wheel turn is provided with an expansion section 26, both of which will be described in detail later in this specification. A curved horizontal tubing section 28 connects the last described wheel turn with drive 12 to complete the endless path of the conveyor.

Each of the wheel turns comprises a tubing section smoothly bent as shown at 39 in FIGS. 2 to 5 to the desired angularity with straight tangent ends 32. The angles on the wheel turns shown are approximately ninety degrees but smaller or larger angle turns can be used as required by the conveyor path.

Brackets such as 34 are suit-ably fastened as by welding to the opposite sides of the extensions 32 and crossmembers are suitably fastened as by bolting to the brackets 34. Bearings such as 38 are suitably fastened as bybolting to the cross-members 36 and serve as lowfriction supports for a shaft 40 which is suitably connected to a wheel 42 provided with a rim 44. The rim 44 is formed with a groove 46 which in cross section has a radius sufiiciently smaller than the largest radius on a solid element of the pusher 10 as shown in FIG. 3 to enable the pushers to wedge into the groove 46 the same way that a V-belt wedges into a V-pulley but usually not to the same extent. This wedging action causes the moving pushers to firmly grip the rim 44 and rotate the wheel 42 at all times when the pushers are moving without slippage. This enables the pusher-linkage assembles to negotiate the turns with elimination of all sliding friction and resisted only by the slight rotating friction created by movement of the bearings 38.

The bends 30 are cut out on the inside as shown at 48 to provide room for the rim 44. The clearance between the edge 48 and the rim 44 is made as small as practical working tolerances permit without rubbing between the rim 44 and bend 30. Side extensions 52 having their inner surfaces flush with the edge 48 and provided with flanges 54 are suitably connected to the bends 30 as shown in FIG. 3 and extend in a curve away from the extensions 32 concentric with the rim 44 and terminate as shown at the point 56 in FIG. 5. The side extensions 52 are each provided with a wall 58 to fill in the gap between the extensions 52 and the tangent extensions 32 and thus support the side extensions 52 as shown in FIGS. 4 and 5.

Curved plates 60 are suitably removably fastened to the flanges 54 as by bolting as shown in FIGS. 3 and 4. Each of the curved plates 60 is provided with a series of elongated slots 62 with a spring blade 64 positioned in each slot 62 as shown in FIGS. 2, 3 and 4. The purpose of these spring blades 64 is to clamp packing gaskets 66 against the side surfaces 68 of the rim 44 and the inside surfaces 70 of the side extensions 52 as well as wedge the gaskets 66 into the clearance 50. This efiectively prevents any leakage of the material being carried through the clearance 50.

A plate 72 is suitably fastened between the walls 58 as shown in FIGS. 4 and 5. A plug 74 shaped as shown in FIGS. 4 and so as to snugly fill the groove 46 of the wheel rim 44 is contacted by the plate 72 so as to completely fill the spaces between the rim 44 and the bends 30 where the rim enters and leaves the bent section of the tubing. A threaded stud 76 is suitably attached to each extension 32 and extends through a plate 78 which is clamped against the plate 72 and the extension 32 by a jam nut 80. An adjustment screw 82 is threaded through the plate 78 and cont-acts a follower plate 84 so that any desired amount of pressure can be exerted against the plug 74 to hold it in the position shown.

It is preferred that the surface of the groove 46 and the sides 68 of the wheel rim 44 be suitably hardened and then finished smooth. Although other materials can be used for the gaskets 66, the preferred material is braided nylon roving impregnated with a mixture of par-afiin and powdered graphite. The same material is preferred for the plugs 74. This material permits the spring strengths of the spring blades 64 and the force with which the plugs 74 are held in place to be made sufiiciently high to prevent any significant amount of material being carried from penetrating between the gasket 66 and the surf-aces 68 of the rim 44 and between the groove surface 46 and the plugs 74 and at the same time does not cause the gaskets 66 and the plugs 74 to exert sufficient drag on the wheel rim 44 to create any substantial resistance to turning of the wheel by the pusher-linkage assembly which would in turn increase the force exerted by the drive 12 to propel the pusher-linkage assemblies through the tubular casing and the Wheel turns. Also, the snug fit between the wheel rim 44 and gaskets 66 and plugs 74 eliminates any significant leakage of the material being carried at the wheel turns.

It will be noted that the construction of the wheel turns provides a through passage for the material in the turns which very closely approximates the same cross section area and shape as the tubular casing at other points than the turns, which eliminates pockets which could cause an accumulation area for the material being carried which could not be cleared out by the pushers.

Some types of materials tend to pack solid in the vertical or inclined up runs of tubular conveyors. This is particularly true where such materials are permitted to remain in the conveyor when it is stationary. For example, when some materials are permitted to remain in tubular conveyor over a week end, they pack so solidly into the lower portions of the vertical up-runs as to make it very ditficult to start the conveyor without seriously overloading the drive and pusher-linkage assemblies. To reduce the prohibitive frictional load imposed by such solidly packed areas, the present invention entails the use of material expansion sections in the turns as well as other sections of a tubular conveyor where such sections would work an advantage. To this end, an expansion section 26 is included in the wheel turn 18 shown to the lower right and an expansion 24 section is included in the vertical uprun straight section shown in FIG. 1. These expansion sections regardless of the position on the conveyor :are constructed the same and can also be applied to simple pipe turns of the type shown in FIG. 6. They are formed by gradually extending a wall 92 of the tubing outwardly away from the opposite wall 94 so as to provide an area which increases in cross sectional area in the direction of movement of the material as shown at 96. The outwardly extending wall 92 continues up beyond the point 98 where the normal casing wall again commences to form an expansion zone 100 for the material. A suitable cover 162 is provided for the expansion zone.

When material is packed into the area 96 and the conveyor is started the increasing cross sectional area of the space 96 enables the pushers to easily lift the material in the are-a 96 upwardly without any jamming action taking place and cause some of this material to enter the expansion zone 100 and thus reduce the amount of material which the pushers must move upwardly at the start which reduces the resistance ofiered by the packed material. As unpacked material passes by the expansion zone 100 the material in this zone is gradually lowered by gravity and mixes in with the other material and is thus predominantly removed. Any material remaining in the expansion zone 100 when the conveyor is being emptied will settle down in the tubing and gradually be elevated by the pushers and thereby completely empty the tubing. By placing expansion sections one above the other as shown in FIG. 1 throughout the extent of the tubular casing which will accumulate material during a stoppage it is possible to completely eliminate the undesirable friction exerted by such jammed areas.

In the operation of tubular conveyors heretofore, much frictional resistance to the movement of the pushers has been created by the weight of the pusher-linkages against the bottom of the tubular casing on the horizontal and near-horizontal runs. This has been particularly true when the material being carried was abrasive.

The tubular conveyor of the present invention overcomes this problem completely by curving the horizontal and near-horizontal runs of the tubular casing downwardly so that the pusher-linkage assemblies hang in a catenary within the tubular casing with at most a light brushing contact with the bottom of the tubular casing so as to lightly sweep the material being carried along without creating any substantial friction between the pushers and the casing. This greatly reduces the force required to propel the pushers along the tubular casing and thus tremendously reduces the wear between the various contacting components as well as reduces any tendency to reduce the particle size of the material being carried.

Although an unexpected increase in the force required to propel the pushers along the tubing might cause the catenary shape of the pusher-linkage assemblies to rise so as to bring the pushers into contact with the top of the inside of the tubular casing, this contact would take place over an area where no material exists because it is not usual practice to operate any tubular conveyor with the tubular casing completely filled so that the abrasiveness of the material would not be a factor during the period of the existence of any such increased force. In other words, the extreme upper portion of the interior of the casing of any tubular conveyor is normally not filled or the conveyor can always be operated at an increased speed to insure that the casing is not filled in the upper area. Rectangular tubing may be employed where such is desired. any given length of pusher-linkage assemblies of a given The ordinates A and B are determined empirically for weight per foot. For example, it is the usual procedure to take pusher-linkage of a given size to fit a tubular casing of given internal diameter and by atcua-l test measurement establish the natural ordinate for catenarys starting with a given length and increasing in length by one foot increments and tabulating these dimensions for design use.

It is desirable that the catenary lengths of pusher-linkage extend tangentially from the rims 44 of the wheel turns 18 and to that end the anigularity of the bend sections 30 will always be made such that the extension 32 which leads into the catenary will conform to the natural pos-i tion of the catenary as shown in FIG. 1 wherein the bends 30 of the two bottom wheel turns 18 are slightly more than 90 degrees and the bend 30 of the top wheel turn 18 to the left is slightly less than 90 degrees; This completely eliminates any rubbing contact between the pushers and the casing tubing.

The use of pusher-linkage assemblies as described in the above mentioned application is of particular advantage in the present invention because the ability of the eccentric pusher elements to rotate about the axis of the linkages insures that the axis of the linkages is always following the shortest path through the tubular casing and thereby creating the minimum of frictional drag between the relatively moving components.

Referring to FIG. 3, it will be noted that the passage area for the material through the wheel turn is free from projections or niches where sharp corners of particles can lodge and cause jamming.

It can thus be seen that the present invention provides a tubular conveyor in which every component in the loaded area cooperates with the other components to produce very low frictional drag between all of the relatively moving components. This makes it possible for the conveyor of the present invention to operate over long and crooked paths and still carry highly abrasive materials with relatively low pulling force applied to the pusherlinkage assemblies. This not only requires much lower power requirement but greatly increases the wear life of the components and also enables many abrasive materials to be conveyed which could not be conveyed before by a tubular conveyor.

The foregoing description of the present invention is to be construed as illustrative only and not lim-itative because many changes can be made in the physical embodiment of the invention without departing from its scope.

The invent-ion having been described, what is claimed 1s:

1. A low friction tubular conveyor comprising a tubular casing to confine the material being carried, pusherlinkage assemblies in the casing, a drive unit to propel the pusher-linkage assemblies along the casing to convey the material, said casing having turns, said casing having a section containing material in which the force of gravity would normally create frictional contact between the casing, the material and the pusher-linkage assemblies, wheellike members rotatably mounted at the turns to support and carry the pusher-linkage assemblies through the turns without sliding frictional contact with anything, and said tubular casing section containing material being curved downwardly between two turns with a curvature which follows the natural catenary of the pusher-linkage assemblies within said curved section whereby the pusher-linkage assemblies forming the catenary are carried predominantly by the wheel-like members at the turns at the ends of said curved section to substantially eliminate sliding frictional contact between the pusher-linkage assemblies within the catenary, the material being carried and said curved casing section.

2. A low friction tubular conveyor comprising a tubular casing, pusher-linkage assemblies in the casing, a drive unit to propel the pusher-linkage assemblies along the casing, a section in said casing which extends upwardly and in which the material being conveyed settles into a densified mass upon stoppage of the conveyor and thereby normally greatly increases the sliding friction between the material and casing upon start-up of the conveyor, an auxiliary wall for the casing extending upwardly adjacent the densified mass area and in prolongation of one side of said casing to provide an interior area in said casing which increases in cross sectional area upwardly and then continues alongside of the casing to provide a parallel path for the material, whereby upon start-up of the conveyor the material in the densified area is elevated by the pushers through the area of increasing cross section and a portion of the material enters intothe parallel path to cause the densified material to expand and thereby reduce the sliding frictional contact with the casing, said casing also having turns, said casing further having a section in which the force of gravity would normally create substantial frictional contact between the pusher-linkage assemblies and the casing, wheel-like members rotatably mounted at the turns to support and carry the pusher-linkage assemblies through the turns without sliding frictional contact with anything, and said last named tubular casing section being curved downwardly between two turns with a curvature which approximates the natural catenary of the pusher-linkage assemblies within said curved section whereby the pusher-linkage assemblies forming the catenary are carried predominantly by the Wheel-like members at the turns at the ends of said curved section to substantially eliminate sliding frictionalcontact between the pusher-linkage assemblies within the catenary and said curved casing section.

3. A low friction tubular conveyor comprising a tubular casing to confinethe material being carried, pusherlinkage assemblies in the casing, a drive unit to propel the pusher-linkage assemblies along the casing, wheel-like members rotatably mounted at selected points along the path of said casing to support the pusher-linkage assemlblies, said casing having a material carrying section between two of said wheel-like members which is curved downwardly with a curvature which approximates the natural catenary of the pusher-linkage assemblies within said curved section whereby the pusher-linkage assemblies forming the catenary are carried predominantly by the wheel-like members at the ends of said curved casing section to substantially eliminate sliding frictional contact between the pusher-linkage assemblies within the catenary, the material being carried and said curved casing section.

4. A low friction tubular conveyor comprising a tubular casing, pusher-linkage assemblies in the casing, a drive unit to propel the pusher-linkage assemblies along the casing, wheel-like members rotatably mounted at selected points along the casing to support the pusher-linkage assemblies, said casing having a section between two of said wheel-like members which is curved downwardly whereby the pusher-linkage assemblies between said two wheel-like members are carried predominantly by said two wheel-like members to reduce frictional rub between the pusher-linkage assemblies and the bottom area of said casing, a section in said casing which is located behind the said curved casing section in the path of movement of said pusher-linkage assemblies, the said section so located extending upwardly and in which the material being conveyed settles into a densified mass upon stoppage of the conveyor and thereby normally greatly increases the slid-.

ing friction between the material and casing upon start-up of the conveyor, an auxiliary wall for the casing extending upwardly adjacent the densified mass area and in prolongation of one side of said casing to provide an interior area in said casing which increases in cross sectional area upwardly and then continues alongside of the casing to provide a parallel path for the material, whereby upon start-up of the conveyor the material in the densified area is elevated by the pushers through the area of increasing cross section and a portion of the material enters into the parallel path to cause the densified material to expand and thereby reduce the sliding frictional contact with the casing and prevent the pulling force required to move the pusher-linkage assemblies through the area of densified material from becoming great enough to cause the pusher-linkage assemblies within the downwardly curved section of the casing to rise upwardly and rub against the top of the curved casing section and thereby undesirably increase the total force which the drive must exert to propel the pusher-linkage assemblies along the casing.

5. A low friction tubular conveyor comprising a tubular casing, pusher-linkage assemblies in the casing, a drive unit to propel the pusher-linkage assemblies along the casing, a turn section in the casing, the turn section being cut away on the inside, a wheel-like member rotatably mounted with its rim in position to support and carry the pusher-linkage assemblies through the turn without sliding frictional contact with anything, the rim of said wheel-like member filling the cut away area of the turn section with the exception of a slight clearance, a gasket, a support which positions the gasket directly over said clearance, and means forcing the gasket into the clearance to seal off the clearance and prevent leakage of conveyed material through the clearance.

6. A low friction tubular conveyor comprising a tubular casing, pusher-linkage assemblies in the casing, a drive unit to propel the pusher-linkage assemblies along the casing, a turn section in the casing, the turn section being cut away on the inside, a wheel-like member having a rim which is grooved peripherally so as to grip the pushers and rotatably mounted with the grooved rim in position to support and carry the pusher-linkage assemblies through the turn without sliding frictional contact with anything with the wheel-like member being positively rotated by the gripping action on the pushers, the rim of said wheel-like member filling the cut away area of the turn section with the exception of a slight clearance, a gasket, a support which positions the gasket directly over said clearance, and means forcing the gasket into the clearance to seal off the clearance and prevent leakage of conveyed material through the clearance.

7. A low friction tubular conveyor comprising a tubular casing, pusher-linkage assemblies in the casing, a drive unit to propel the pusher-linkage assemblies along the casing, a turn section in the casing, the turn section being cut away on the inside, a Wheel-like member having a rim which is grooved peripherally so as to grip the pushers and rotatably mounted with the grooved rim in position to support and carry the pusher-linkage assemblies through the turn without sliding frictional contact with anything with the wheel-like member being positively rotated by the gripping action on the pushers, the rim of said wheel-like member filling the cut away area of the turn section with the exception of a slight cleartime along each side of the rim and the cross sectional area of the rim groove where the rim enters and leaves the turn section, a gasket support extending along each clearance, a gasket on each support and positioned directly over the clearance, means forcing each gasket into the adjacent clearance, a plug support at the point where the rim enters the turn section and a plug support at the point where the rim leaves the turn section, a plug carried by each support, and means forcing each plug into the space between the rim groove and the turn section casing.

8. A low friction tubular conveyor comprising a tubular casing, pusher-linkage assemblies in the casing, a drive unit to propel the pusher-linkage assemblies along the casing, a section in said casing which extends upwardly and in which the material being conveyed settles into a densified mass upon stoppage of the conveyor and thereby normally increases the sliding friction between the material and casing upon start-up of the conveyor, an auxiliary wall for the casing extending upwardly adjacent the densified mass area and in prolongation of one side of said casing to provide an interior area in said casing which continues to increase in cross sectional area upwardly as it extends upwardly and then continues alongside of the normal casing wall to provide a parallel path for the material, whereby upon start-up of the conveyor the material in the densified area is elevated by the pushers through the area of increasing cross section and a portion of the material enters into the parallel path to enable the densified material -to expand and thereby reduce the sliding frictional contact with the casing,

9. A low friction tubular conveyor as defined in preceding claim 7 in which the tubular casing in both the straight and turn sections is approximately circular in cross section.

References ited by the Examiner UNITED STATES PATENTS Re. 22,789 9/1946 Brunner 198-168 1,117,939 11/1914 Zublin 198-168 X 2,095,315 10/1937 Crocker 198-168 X 2,465,287 3/1949 Sinden 198-168 2,575,551 11/1951 Frechin 198-168 FOREIGN PATENTS 587,723 5/ 1947 Great Britain.

EVON C. BLUNK, Primary Examiner.

EDWARD A. SROKA, Examiner. 

1. A LOW FRICTION TUBULAR CONVEYOR COMPRISING A TUBULAR CASING TO CONFINE THE MATERIAL BEING CARRIED, PUSHER LINKAGE ASSEMBLIES IN THE CASING, A DRIVE UNIT TO PROPEL THE PUSHER-LINKAGE ASSEMBLIES ALONG THE CASING TO CONVEY THE MATERIAL, SAID CASING HAVING TURNS, SAID CASING HAVING A SECTION CONTAINING MATERIAL IN WHICH THE FORCE OF GRAVITY WOULD NORMALLY CREATE FRICTIONAL CONTACT BETWEEN THE CASING, THE MATERIAL AND THE PUSHER-LINKAGE ASSEMBLIES, WHEELLIKE MEMBERS ROTATABLY MOUNTED AT THE TURNS TO SUPPORT AND CARRY THE PUSHER-LINKAGE ASSEMBLIES THROUGH A TURNS WITHOUT SLIDING FRICTIONAL CONTACT WITH ANYTHING, AND SAID TUBULAR CASING SECTION CONTAINING MATERIAL BEING CURVED DOWNWARDLY BETWEEN TWO TURNS WITH A CURVATURE WHICH FOLLOWS THE NATURAL CATENARY OF THE PUSHER-LINKAGE ASSEMBLIES WITHIN SAID CURVED SECTION WHEREBY THE PUSHER-LINKAGE ASSEMBLIES FORMING THE CATENARY ARE CARRIED PREDOMINANTLY BY THE WHEEL-LIKE MEMBERS AT THE TUNS AT THE ENDS OF SAID CURVED SECTION TO SUBSTANTIALLY ELIMINATE SLIDING FRICTIONAL CONTACT BETWEEN THE PUSHER-LINKAGE ASSEMBLIES WITHIN THE CATENARY, THE MATERIAL BEING CARRIED AND SAID CURVED CASING SECTION. 